Most land-dwelling animals with skeletons (exo or endo) have the ability to jump. It is of particular importance to survival, as running primarily consists of a long series of jumps. Without the ability to jump, a robot's freedom to move around is limited, something that is particularly true of smaller robots for which even relatively narrow trenches or low walls can prove too much of an obstacle. A robotics group at the University of Pennsylvania (UPenn) has taught a six-legged crawling robot to jump, giving it remarkable acrobatic capabilities.